Fuel lance

ABSTRACT

A lance ( 3 ) for introducing a fuel into a mixing path ( 2 ) of a burner ( 1 ) which is provided with a swirler for producing a swirled combustion air flow, especially a burner of a turbine plant, includes a lance head ( 5 ), a fuel feed ( 8 ) and an oxidator feed ( 10 ). The lance head ( 5 ) projects into the mixing path ( 2 ), has at least one fuel nozzle ( 6 ) for injection of the fuel into the mixing path ( 2 ), and also has at least one oxidator outlet orifice ( 7 ) for introducing an oxidator into the mixing path ( 2 ). The fuel feed ( 8 ) extends in the lance ( 3 ) and is connected to the at least one fuel nozzle ( 6 ). The oxidator feed ( 10 ) extends in the lance head ( 5 ) and is connected to the at least one oxidator outlet orifice ( 7 ). In order to improve the operation of the burner ( 1 ), the at least one oxidator outlet orifice ( 7 ) is located centrally on the lance head ( 5 ), and the at least one fuel nozzle ( 6 ) is installed on the lance head ( 5 ), being offset radially outwards with regard to the at least one oxidator outlet orifice ( 7 ).

This application is a Continuation of, and claims priority under 35 U.S.C. § 120 to, International application no. PCT/EP2006/067525, filed 18 Oct. 2006, and claims priority therethrough under 35 U.S.C. §§ 119, 365 to Swiss application no. 01769/05, filed 4 Nov. 2005, the entireties of which are incorporated by reference herein.

BACKGROUND

1. Field of Endeavor

The invention relates to a lance for introducing a fuel into a combustion chamber of a burner which is provided with a swirler, especially a burner of a turbine plant.

2. Brief Description of the Related Art

DE 100 50 248 A1 discloses such a lance for a burner, which basically includes a swirler for producing a swirled combustion air flow and a device for introducing at least a quantity of fuel into this combustion air flow, which includes a lance head, a fuel feed, and an oxidizer/oxidator feed. The lance head in the installed state projects into the combustion chamber, has a central fuel nozzle for injecting the fuel into the combustion chamber, and also has an oxidator outlet orifice for introducing the oxidator into the combustion chamber. The fuel feed extends in the lance and is connected to the fuel nozzle. The oxidator feed extends in the lance head and is connected to the oxidator outlet orifice. In the disclosed lance, the fuel nozzle is installed centrally on the lance head so that the injected fuel enters the combustion chamber coaxially to the longitudinal axis of the lance. The oxidator outlet orifice is designed in annular form and coaxially encloses the fuel nozzle. As a result, the oxidator also emerges axially from the lance head and in the process envelops the injected fuel. The oxidator, which as a rule is air, which is additionally introduced into the combustion chamber through the lance head, is necessary for cooling and for purging of the lance head.

In the burner with a swirler which is disclosed in DE 100 50 248 A1, a vacuum is produced on the axis so that an intense suction action prevails in the center, which has a great significance for the burner dynamics.

In larger burners of this type, therefore burners with larger output or larger fuel conversion, as the case may be, it has been shown that introducing of fuel through the lance leads to a comparatively poor mixing through, and, therefore, to relatively unfavorable combustion reactions with increased pollutant emission.

SUMMARY

One of numerous aspects of the invention deals with the problem of specifying an improved embodiment for a lance of the aforementioned type, which can be characterized by an improved fuel injection.

Another aspect of the present invention is based on the general idea of locating at least one oxidator outlet orifice centrally on the lance head and installing the at least one fuel nozzle to be offset radially outwards in relation to it. The injection of the fuel, therefore, takes place on a relatively large radius with regard to the longitudinal center axis of the lance. Furthermore, the injection of the fuel takes place radially outside the oxidator which is fed centrally through the lance. The two media (oxidator/fuel) in this case are guided past each other by crossing distribution hole systems.

It has been shown that these measures lead to an improved mixture formation and to an improved combustion reaction, and, therefore, lead to reduced pollutant emissions. At the same time, however, the cooling and purging function of the centrally supplied oxidator is maintained.

According to preferred embodiments, the fuel feed can have a fuel line extending in the lance. Furthermore, an annular fuel passage which is located in the lance head can be provided, to which annular fuel passage on the one side is connected the at least one fuel nozzle, and which annular fuel passage on the other side is connected to the fuel line by fuel connecting passages. By this constructional form, the at least one fuel nozzle can be displaced radially outwards especially far since the fuel passages can be designed so that they can connect the centrally located fuel line to the annular fuel passage which, more or less, can have a radius of any size. Instead of a common annular fuel passage, a plurality of separate supply passages can also be provided, which in each case connect one of the fuel nozzles to one of the fuel connecting passages.

Also advantageous are embodiments in which the oxidator feed has an oxidator chamber located centrally in the lance head, the end of which, which is open towards the combustion chamber, forms the oxidator outlet orifice. Furthermore, a plurality of oxidator connecting passages can be provided, which in each case connect the oxidator chamber to an oxidator inlet orifice which is located radially on the outside on the lance head. By inclusion of the oxidator chamber, a relatively large surface which is impactable by the oxidator is provided inside the lance head, which improves the cooling action of the oxidator flow.

Further important features and advantages of the invention are apparent from the drawings and from the associated figure description with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Two preferred exemplary embodiments of the invention are shown in the drawing and are explained in detail in the subsequent description.

In the drawing:

FIG. 1 shows a much simplified axial section through a burner which is equipped with a lance and a swirler, in the region of a lance head, in a first embodiment of the invention; and

FIG. 2 shows a much simplified axial section through a burner equipped with a lance and a swirler, in the region of a lance head, in a second embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 accordingly illustrates a burner 1, which is only partially shown, which is equipped with a swirler, which is not shown, for producing a swirled combustion air flow, and a mixing path 2 which leads to a combustion chamber, which is not shown. This mixing path 2 can also be designated as a combustion chamber. In this case, the burner 1 can be a component part of a turbine plant, especially a gas turbine plant. The burner 1, in the head section on the inlet side which is shown here, is provided with a lance 3, by which a fuel can be introduced into the mixing path 2. As is generally known, such lances are separate component parts, which are movably installed in the burner and which can also be relatively simply withdrawn, should the occasion arise.

The lance 3 includes a lance shank 4 and also a lance head 5 which is installed or formed on the lance shank 4 on the end which is allocated to the burner 1. In the installed state which is shown, the lance head 5 projects into the mixing path 2. In this connection, the embodiment which is shown here is preferred, in which the lance 3 and the burner 1 are installed coaxially to each other so that the lance head 5 projects coaxially into the mixing path 2.

The lance head 5 has at least one fuel nozzle 6, by which the fuel can be injected into the mixing path 2. Preferably, the lance head 5 has a plurality of such fuel nozzles 6, of which only one is visible in FIG. 1, however, on account of the selected cutting plane. In this case, the fuel nozzles 6 are installed on the lance head 5, being distributed in the circumferential direction and spaced apart from one another in the circumferential direction. For example, the lance head 5 is equipped with four such fuel nozzles 6 which are installed with them being displaced relatively to one another in the circumferential direction by 90 in each case.

Furthermore, the lance head 5 is equipped with at least one oxidator outlet orifice 7, by which an oxidator can be introduced into the mixing path 2. Preferably, only a single such oxidator outlet orifice 7 is provided.

With regard to the fuel, it is preferably a liquid fuel, such as diesel oil. It can also be a gaseous fuel, such as natural gas. With regard to the oxidator, it is preferably a gaseous oxidator, which, as a rule, is air.

The lance 3 is also equipped with a fuel feed 8 which is connected to the fuel nozzles 6. The fuel feed 8 extends inside the lance 3 and, in the installed state, is connected to an external fuel supply 9, which is symbolized in FIG. 1 by an arrow. Furthermore, the lance 3 includes an oxidator feed 10. The oxidator feed 10 is connected to the oxidator outlet orifice 7 and extends inside the lance head 5. In the installed state, the oxidator feed 10 is connected to an external oxidator supply 11, which is symbolized by an arrow, and which includes, for example at least one oxidator line 12 extending in the burner 1.

The lance 3 which is shown here has the specific feature that the oxidator outlet orifice 7 is located centrally on the lance head 5. As a result of this, the oxidator during operation can be introduced into the mixing path 2 coaxially to the longitudinal center axis 13 of the lance 3. Furthermore, in the lance 3 which is shown here, the fuel nozzles 6 are installed on the lance head 5 with them being offset radially outwards with regard to the oxidator outlet orifice 7. As a result of this, the fuel during operation can be injected into the combustion chamber 2 on a relatively large radius. Moreover, the place of the fuel injection, therefore, in any event is located radially outside the centrally fed oxidator. The injection of the fuel itself at the aforesaid place takes place then preferably at an angle in the radial and tangential direction, which is explained further in still more detail below.

This constructional form has several advantages. For one thing, the oxidator which is fed through the lance 3 can fulfil its cooling function and cleaning function. For another thing, the oxidator which is introduced through the lance head 5 for cooling and cleaning does not influence the fuel injection. Moreover, the fuel injection, which takes place radially further out, leads to an improved mixing through with a main oxidator flow which is introduced into the mixing path 2 at a place which is not shown.

In the preferred embodiment which is shown here, the fuel feed 8 includes a fuel line 14 which extends in the lance 3. For this purpose, the lance shank 4 is designed as a tube. The fuel line 14 is connected to the fuel supply 9. In addition, the fuel feed 8 can have an annular fuel passage 15 which is located in the lance head 5. The annular fuel passage 15 is connected to the fuel nozzles 6. Furthermore, the annular fuel passage 15 extends coaxially to the longitudinal center axis 13 of the lance 3. It is noteworthy that the annular fuel passage 15 has a larger diameter than the fuel line 14 and a larger diameter than the lance shank 4. Instead of an annular fuel passage 15 which is commonly allocated to all the fuel nozzles 6, a plurality of axially extending supply passages or supply holes can also be provided, which in each case are connected to one of the fuel nozzles 6. These supply passages can even out the flow to the respective fuel nozzle 6 and avoid so-called “dead water regions” close to the fuel nozzles 6, which simplifies the purging when the fuel feed is shut off.

Furthermore, the fuel feed 8 can have a plurality of fuel connecting passages 16. These fuel connecting passages 16 are located in the lance head 5, in fact in a transition section 17 by which the lance head 5 merges into the lance shank 4. This transition section 17 is conically designed in this case, and has a cross section which reduces in the direction of the lance shank 4. The conical transition 17 achieves the effect that the lance head 5 outside the transition section 17 has a noticeably larger external cross section than the lance shank 4. As a result of this, an especially large radius or distance to the longitudinal center axis 13 for the positioning of the fuel nozzles 6 can be achieved.

The fuel connecting passages 16 extend axially from the centrally located fuel line 14 and also extend radially outwards as far as the annular fuel passage 15. Preferably, a plurality of fuel connecting passages 16, for example three, is provided to supply the annular fuel passage 15 with enough fuel. In principle, even a single fuel connecting passage 16 can be sufficient. If, instead of the common annular fuel passage 15, the separate supply passages or supply holes, which were mentioned further up, are used, these are connected to such a fuel connecting passage 16 in each case.

The oxidator feed 10 preferably includes an oxidator chamber 18 which has one axial end open towards the mixing path 2, which forms the oxidator outlet orifice 7. The oxidator chamber 18 is located centrally in the lance head 5 for this purpose. In a circular oxidator outlet orifice 7, the oxidator chamber 18 has a corresponding cylinder section which is adjacent to the oxidator outlet orifice 7. Furthermore, the oxidator chamber 18 has a truncated cone section on the end remote from the oxidator outlet orifice 7.

The oxidator feed 10 also includes a plurality of oxidator inlet ports 19 which in each case are located on the lance head 5 radially on the outside, preferably on its transition section 17. These oxidator inlet ports 19 can be connected to the oxidator supply 11, for example by the oxidator lines 12. In addition, the oxidator feed 10 includes a plurality of oxidator connecting passages 20 which in each case connect one of the oxidator inlet ports 19 to the oxidator chamber 18, and for this purpose lead into its truncated cone section. The oxidator connecting passages 20 are also located in the lance head 5 and preferably in its transition section 17. In this case, the oxidator connecting passages 20 extend axially from the respective outer lying oxidator inlet port 19 and radially inwards to the oxidator chamber 18.

In the embodiment which is shown here, therefore, a constellation is produced, in which the annular fuel passage 15 coaxially encloses the oxidator chamber 18. In this way, the fuel is located in the lance head 5 radially further out than the oxidator. The fuel connecting passages 16 and the oxidator connecting passages 20 are arranged in the lance head 5 so that they alternate with each other in the circumferential direction. Expediently, therefore, the same number of oxidator connecting passages 20 is provided as there are fuel connecting passages 16. The fuel flow which is radially guided from the inside outwards, and the oxidator flow which is radially guided from the outside inwards, cross over in the lance head 5 or in the transition section 17, as the case may be, but in passages 16, 20 which are separated from each other and sealed in relation to each other.

The lance head 5, in the example which is shown, is dimensioned so that the radius upon which the fuel nozzles 6 are located is larger than the radius of the lance shank 4. The fuel nozzles 6, therefore, are located radially further out than an external cross section of the lance 3 outside the lance head 5. The fuel nozzles 6 basically can be designed so that they inject the fuel obliquely into the mixing path 2 with regard to the axial direction of the lance 3, as shown. Furthermore, the fuel nozzles 6 in addition can also be designed so that they inject the fuel obliquely into the mixing path 2 with regard to a central longitudinal plane of the lance 3, and so with regard to a plane including the longitudinal center axis 13. The fuel injection, therefore, can take place approximately in the direction of, or in the opposite direction to, a swirled flow which is formed in the mixing path 2 by a corresponding tangential introduction of the main oxidator flow.

In the example which is shown, the lance head 5 is assembled from a basic body 21 and a sleeve component 22. For this, the sleeve component 22 is fitted coaxially onto the basic body 21 and fastened to it by welded connections 23.

The exemplary embodiment according to FIG. 2 differs from the exemplary embodiment which is shown in FIG. 1 only in that the oxidator line 12 is located axially, i.e., coaxially to the fuel feed 8, so that the air can flow in axially. In the transition section 17 of the lance head 5, the air is then directed from the outside diameter towards the center of the lance, while the fuel (for example, oil) is transferred from the center to the outside diameter. As before in the first exemplary embodiment, the oxidator injection and the fuel injection from the lance 3 into the mixing path 2 are realized on an almost identical plane so that the axial oxidator feed is completely enclosed by a fuel-guiding plenum.

LIST OF DESIGNATIONS

-   -   1 Burner     -   2 Mixing path     -   3 Lance     -   4 Lance shank     -   Lance head     -   6 Fuel nozzle     -   7 Oxidator outlet orifice     -   8 Fuel feed     -   9 Fuel supply     -   10 Oxidator feed     -   11 Oxidator supply     -   12 Oxidator line     -   13 Longitudinal center axis of 3     -   14 Fuel line     -   15 Annular fuel passage     -   16 Fuel connecting passage     -   17 Transition section of 5     -   18 Oxidator chamber     -   19 Oxidator inlet port     -   20 Oxidator connecting passage     -   21 Basic body     -   22 Sleeve component     -   23 Welded connection

While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein. 

1. A lance for introducing a fuel into a mixing path of a burner having a swirler for producing a swirled combustion air flow, the lance comprising: a lance head which, when installed, projects into the mixing path, the lance head having at least one fuel nozzle for injection of the fuel into the mixing path and at least one oxidator outlet orifice for introducing an oxidator into the mixing path; a fuel feed extending in the lance and connected to the at least one fuel nozzle; an oxidator feed extending in the lance head and connected to the at least one oxidator outlet orifice; wherein the at least one oxidator outlet orifice is located centrally on the lance head; and wherein the at least one fuel nozzle is positioned on the lance head and offset radially outwards with respect to the at least one oxidator outlet orifice.
 2. The lance as claimed in claim 1, wherein at least one of: the fuel feed has a fuel line extending in the lance; or the fuel feed has a supply passage located in the lance head for each fuel nozzle, to which supply passage is connected a respectively associated fuel nozzle; or the fuel feed has an annular fuel passage located in the lance head, to which annular fuel passage is connected the at least one fuel nozzle; or the fuel feed has a plurality of fuel connecting passages which connect the annular fuel passage or the supply passages to the fuel line.
 3. The lance as claimed in claim 1, wherein at least one of: the oxidator feed has an oxidator chamber located centrally in the lance head, the oxidator chamber having an end open towards the mixing path forming the oxidator outlet orifice; or the oxidator feed has an inlet port positioned radially on the outside of the lance head, and a plurality of oxidator connecting passages which in each case connect the oxidator chamber to the oxidator inlet port.
 4. The lance as claimed in claim 2, wherein at least one of: the oxidator feed includes a plurality of oxidator connecting passages and the fuel feed includes a plurality of fuel connecting passages, the oxidator connecting passages and the fuel connecting passages positioned in the lance head circumferentially alternating with each other; or the oxidator feed has an oxidator chamber and the fuel feed has an annular fuel passage located in the lance head which coaxially encloses the oxidator chamber.
 5. The lance as claimed in claim 1, wherein at least one of: the lance head has a larger external cross section than a lance section adjacent to the lance head; or the at least one fuel nozzle is positioned on a larger radius than the external cross section of the lance outside the lance head; or the lance head has a conical transition section by which the lance head is connected to an adjacent lance section.
 6. The lance as claimed in claim 5, wherein the lance head has a conical transition section by which the lance head is connected to an adjacent lance section, and wherein at least one of: the oxidator feed has an inlet port located in the transition section; or the fuel feed includes a plurality of fuel connecting passages located in the transition section; or the oxidator feed includes a plurality of oxidator connecting passages located in the transition section.
 7. The lance as claimed in claim 1, wherein at least one of: the at least one oxidator outlet orifice comprises only a single central oxidator outlet orifice; or the at least one fuel nozzle comprises a plurality of circumferentially distributed fuel nozzles on the lance head.
 8. The lance as claimed in claim 1, wherein the at least one fuel nozzle is configured and arranged so that the at least one fuel nozzle injects fuel obliquely into the mixing path relative to the axial direction of the lance, with respect to a central longitudinal plane of the lance, or both.
 9. The lance as claimed in claim 1, further comprising at least one of: liquid fuel in the fuel feed; or oxidator in the oxidator feed.
 10. A burner comprising: a burner body; a swirler configured and arranged to produce a swirled combustion oxidator flow; a mixing path formed in the burner body; and a lance according to claim 1 projecting into the mixing path. 